In 1947, Jose Moretzsohn De Castro, a Brazilian medical doctor, described his 9 years of personal experience with cineradiography focusing on evaluation of function of internal organs. [3]
In 1956 J. William Fielding attempted to describe normal motion in the cervical spine as visualized by cineradiography. [4]
Since that time, interest in the application of cineradiography to the study of the musculoskeletal system has grown, and there have been numerous articles published in the literature on this topic. Most of the literature to date deals with the cervical spine, however, recent attention has also focused on the lumbar spine.
It appears that the only quantification which can be done with real-time fluoroscopy is using a digitizer.[9,10] In general, the expense and training necessary to do good fluoroscopic studies of the spine renders this modality best suited to the laboratory.[11]
"Any procedure that seeks to quantify the difference between normal and abnormal should ideally fulfill each of the following criteria:
There is no known in vivo standard by which videofluoroscopy can be judged. This situation is not unique to the validation of chiropractic procedures. "Test/re-test reliability is difficult to assess when the biological material with which one is working changes with each test".[12] Internal consistency is the ability of a test to change its outcome as outcomes of other tests change, however, this relies on the validity of said tests (which cannot be done here as there are no scientifically valid means for determining normal spinal kinematics in vivo).[12,13,14,15,16,17,18,19]
The only method which remains is observer variability (i.e.: the same results noted by multiple examiners or a single examiner on multiple occasions). This is where the majority of the studies on VF have been done.[12]
The only foreseeable means of quantifying intersegmental motion in vivo is via advanced technology imaging systems such as digitized videofluoroscopy.[12] It is important to remember that demonstrating reliability in measurement in no way guarantees clinical correlation or utility.[12]
Dimnet et al., in 1982 stated that the cineradiographic literature to date dealt largely with qualitative results and inexactly defined parameters, and that interpretation of the same studies was difficult for that reason.[16]
Despite numerous attempts to describe normal and abnormal motions in the cervical spine, Bell in 1990 concluded that "normal and abnormal motion need to be described with more precision" and that, in fact, at that time "no developed method yet exists for quantifying fluoroscopic images".[2]
Breen et al., in a study with digital VF on a single asymptomatic subject, noted the following: "intersegmental coronal plane rotation was not always regular, and if this phenomenon is common, similar degrees of irregularity in symptomatic subjects cannot be regarded as pathological."[8] Again, VF was able to demonstrate motion, but the clinical significance of such motion remains undefined.
A review of the literature dealing with normal cervical spine motion reveals that other than a study by Taylor and Skippings,[17] no properly controlled, well-designed studies with well-defined selection criteria exist. Most of the literature merely describes normal motion as the authors have witnessed it. It is from these descriptions of normal that an attempt at defining abnormal has been made.
It would appear that for the purpose of visualizing real-time spinal motion, VF is excellent, but as one attempts to quantify that motion, issues of reliability become very sticky.[20] Without digitization, numeric quantification of real-time VF is not reasonably possible.[11]
Continued Next Month.
EQUIPMENT
A variety of types of machines are currently available. For clinical utility, ALARA needs to be observed. [5,6,7] Breen was able to reduce dosage in each plane to less than the same assessment with plain films.[8]
VALIDATING THE PROCEDURE
Breen describes a logical approach to validation of testing procedures as follows:
1) Calibration against a known standard.
All this assumes a strong quantitative element in the procedure and its unambiguous definition."[12]
2) Test/re-test reliability.
3) Internal consistency.
4) Observer variability.
DEFINITION OF NORMAL
As early as 1958 Kottke and Lester stated "before this technic (sic) can be used to fullest value, standards of normal variations of vertebral motion will have to be established as a basis for evaluating abnormal cervical motion."[15]
MEASUREMENT
Measurement accuracy with videofluoroscopy is nearly impossible to achieve without digitization. The sources of error are nearly infinite, specifically with respect to vertebral position.[11]
Dr. Knudsen is a board certified chiropractic radiologist (D.A.C.B.R.) and is Director of Clinical Diagnostic Imaging at National College of Chiropractic in Lombard, Illinois. For more information about Dr Knudsen’s radiology consulting services, MRI imaging, or quality control issues, please call Dr. Knudsen at (800)469-9729.